In nature, there are approximately 600 types of carotenoids, but only six of them can be used for industrial production by manufacturers including Roche Company and BASF Company, and lycopene, as an important product, plays a key role in free radical removal, anti-aging, tumor inhibition, treatment for heart disease and the like and is widely applied to drugs, food additives and feed additives. Roche Company has developed a Wittig reaction-featured synthetic route in which expensive and toxic raw material triphenylphosphine is used, and triphenylphosphine is used in a variety of other early synthesis methods as well.
Babler J. H et al. reported a novel Wittig-Horner reaction-featured method for the synthesis of lycopene in WO 0031086, in which 3,7,11-trimethyl-2,4,6,10-tetraene-dodecyl diethyl phosphonate is used as key intermediate and condensed with decadialdehyde under the catalysis of base to prepare lycopene, and the synthesis steps are as follows:
At first, pseudoionone (2) reacts with acetylene anion to obtain tertiary alcohol (7) (i.e. 3,7,11-trimethyl-4,6,10-dodecyl triene-1-alkynyl-3-alcohol):

Then, the resultant tertiary alcohol (7) reacts with diethyl chlorophosphite to obtain propadiene pentadec-carbon phosphonate (6) (i.e. 3,7,11-trimethyl-1,2,4,6,10-pentaene-dodecyl diethyl phosphonate):

Afterwards, the propadiene pentadec-carbon phosphonate (6) is partially reduced and converted into pentadec-carbon phosphonate (5) (i.e. 3,7,11-trimethyl-2,4,6,10-tetraene-dodecyl diethyl phosphonate)

Finally, the pentadec-carbon phosphonate (5) and decadialdehyde (8) (i.e. 2,7-dimethyl-2,4,6-trieneoctane-1,8-dialdehyde) are condensed under the catalysis of base to prepare lycopene (1):

In the synthesis method above, the new compound 2,4,6,10-tetra-double bond pentadec-carbon phosphonate (5) is used as key intermediate, which avoids the use of triphenylphosphine; besides, with the pseudoionone as raw material, the target product lycopene can be obtained only by reactions in four steps, so the route is simple and convenient and tremendous progress is achieved compared with previous methods. However, this route has some problems: first, it is difficult, to a certain extent, to obtain propadiene pentadec-carbon phosphonate (6) by means of the reaction between tertiary alcohol (7) and diethyl chlorophosphite; second, it is difficult to grasp the reduction technology for selectively reducing propadiene pentadec-carbon phosphonate (6) into pentadec-carbon phosphonate (5).